Montgomery County ADU Ceiling Height and Other Regulations

[Joseph Ayoub]

Hey fellow DMV community! Long post here, but I am considering putting an offer on a property in Montgomery County, Maryland and converting the basement into an accessory dwelling unit. I called the Montgomery County Licensing and Registration office with my questions and they told me to just "look online" for the regulations, so here is what I found:

Class 3 ADU Requirements (last updated 3/4/2020 after the new ADU law in MoCo passed)

2020 MoCo Housing Code Enforcement Guide

In the Housing Code Enforcement Guide, it states room length and width requirements for "minimum dwelling standards" and "habitable space." There is no ceiling height requirement for these two categories. It states that for sleeping areas, "50% of the ceiling height must be at least seven feet high" but "Basements must have a minimum ceiling height of six feet eight inches." 

In the ADU requirements, it states specifically "Basement Ceiling Heights: Accessory Dwelling Units located in finished basements or cellars must have a ceiling height of at least 6'8", except a beam, girder, duct or other obstruction may project to within 6'4" of the finished floor." It makes no mention of sleeping area height.

So my questions are the following:

• In order to create a basement ADU with bedrooms, what is the ceiling requirement? Does 50% of ceiling height have to be 7' or is the blanket 6'8" acceptable since it is a basement?
• If I sell the house (or move out and rent the house) and remove the stove in the basement ADU kitchen, would the 6'8" basement bedroom still be useable as a bedroom? Moreover, would the entire basement area now be considered "finished space" and add to the square footage?
• Alternatively, if finishing the space only meets ADU requirements (but not standard finished space or bedroom requirements) could I keep the space finished and market the property as a single family home with an ADU? Does that add value to a property?

My goal here is to determine what value (if any) will come from finishing the basement based on these regulations in MoCo. The property I'm considering is an older home that is cutting it close with some of these ceiling heights in the basement. Based on estimates I have received for other homes, I'm certain that digging out the entire basement would definitely throw the numbers off. 

Any suggestions around this topic would be really great. Or, if anyone has contacts/contractors I can reach out to for a definite answer in MoCo as part of my own due diligence, that would be a step in the right direction. Appreciate any insight and help that y'all can provide!

[Payton Chung]

IANAL, but I suspect that the Housing Code guide is assuming that you know the Building Code definition: that "habitable space" is 7'+ and that basements that are not habitable must be 6'8"+.

So any space <7' is not supposed to be counted as habitable square footage for building code purposes (though there are some exceptions). But yes, if it meets the ADU definition, you could market the house as having a legal basement ADU, and that should have some value on the market.

There are some architects in DC who do a lot of ADUs and particularly English basement units; since the building code is almost identical, I'm sure they'd be well versed in the code particulars.

[Bruce Woodruff]

@Payton Chung is right. You're looking for 'living space' here, so you must comply with those requirements. Ceiling height, egress, heat, electrical, etc.....